Photographic layers suitable for the silver dyestuff bleaching process



United States Patent 61 9 Claims. (Cl. 9699) In the subtractive color photographic process for the production of color transparencies and color pictures to be viewed by reflected light there is required ablue component, color image of which the blue dyestufi has an absorption maximum at about 600 to 640 m and is as transparent as possible in the region from 400 to about 500 m When the blue component color image is produced by the known silver dyestuff bleaching process, there are generally used blue azodyestuflfs which are bleached in suitable bleaching baths depending on the quantity of image silver locally present.

Various blue azo-dyestuffs are known for use in producing a blue component color image by the silver dyestutf bleaching process. Dyestufis of this kind also exist among the ordinary commercial direct dyestufis, for example, the disazo-dyestulfs that are obtained by coupling tetrazotized 3 3'-dirnethoxy 4: 4'-diamino-l: l-diphenyl on both sides with 1-amino-8-hydroxynaphthalene-3:6- or -2:4-disulfonic acid. To a large extent these dyestufls meet the above requirements. However, they have the disadvantage that where the image silver has decomposed the dyestutf to a low color density of about 0.1 to 0.3 logarithmic value a change in shade towards a reddish blue takes place. An explanation of this phenomenon is that the disazo-dyestuffs decompose in stages via the monoazodyestuifs as follows:

The present invention is based on the observation that dyestuffs obtained from a tetrazotized 3:6:3:6'-tetraalkoxy-4:4-diaminodiphenyl and l-amino 8 hydroxynaphthalene disulfonic acids do not exhibit the above disadvantage in the silver dyestuff bleaching process.

The invention therefore provides photographic layers 3,Z5 ,43 Patented July 5, 1966 suitable for the silver dyestuff bleaching process which contain a dyestufi of the general formula in which R and. R each represent the radical of a 1- amino-8 hydroxy-naphthalene sulfonic acid, bound to the azo linkage in a position vicinal to the hydroxyl group, and at least one of the said radicals contains two sulfonic acid groups, and in which X and X represent an alkyl group which may by interrupted by an ether bridge.

The dyestuffs of the Formula 1 can be obtained by coupling a tetrazo-compound of a diamine of the formula X1-O l )Xz (in which X and X have the meanings given above) to from a hydrazo-compound of the formula (')X1 Xr-O X2(|) (F-X2 followed by so-called benzidine rearrangement.

The compounds of the Formulae 2, 3 and 4 contain alkyl groups which are bound to the benzene nuclei through an oxygen atom and which may themselves be interrupted by an oxygen atom, that is to say, an ether bridge. Two different or identical groups of that kind may be bound to a single benzene nucleus. The groups X and X advantageously contain at most 5 carbon atoms. As examples of -.-OX and/ or OX there may be mentioned n-butoxy, n-propoxy, isopropoxyand B-methoxy-ethoxy (OCI -I CH O-.CH groups but more especially ethoxy and methoxy groups. Accordingly, there may be used as diamines of-the Formula 2 for making the disazodyestutfs, for example, 3:6:3':6'- tetra-ethoxy-4:4'-=diamLinodiphenyl and, advantageously,

3 :6: 3 6'-tetramethoxy-4.:4'-diaminodiphenyl.

As coupling components for making the disazodyestuffs of the Formula 1 there are used 'l-amino-8-hydroxy naphthalene sulfonic acids. The tetrazo-compounds of the diarnines of the Formula2 are coupled on at least one side with a 1amino-8-hydroxynaphthalene disulfonic acid, and they may be coupled on the other side with a l-amino- S-hydroxynaphthalene monosulfonic acid, such as 1- amino-S-hydroxynapthalene-4-sulfonic acid. As examples of l-amino-8=hydroxynapthalene disulfonic acids there may be mentioned l-amino 8 hydroxynapthalene 2:4- -3 :5-, -3:6 and 4:6-disulfonic acid. The amino group in the 1-position may be a primary amino group or, especially in the case of the 3 :6- and the 4:6-disulfonic acid, a substituted amino group, for example, a monoalkylamino or dialkyl amino group, such as a monoor di-methylprocess, or they can be rendered completely fast to difamino, monoor di-ethylamino, a hydroxyalkylamino products of dicyandiamidine with form-aldehyde. Angroup, such as p-hydroxyethylamino, or phenylamino fusion with suitable agents, such as biguanide or reaction group or especially an acylamino group, such as an acetylother method of enhancing the fastness to diffusion conamino or propionylamino group. Among the acylamino sists in precipitating the dyestulf dissolved in the gelatine groups there may (be mentioned more especially those in a very fine form by the addition of an alkaline earth containing a benzene nucleus which may be further subsalt, for example, barium chloride, dissolved in water or stituted, such as the benzoyl amino-, dichloro-benzoyla gelatine solution. For this purpose zinc or lead salts amino-, para-benzoylamino-benzoylaminomay also be used.

The fastness to light of the finished blue component NH OCCBH4OCCGH5) color image can be substantially improved by treatment or toluene-sulfonylamino group. with an agent yielding nickel or more especially with an As stated above, asymmetrical diazo-dyestuffs can be agent yielding copper, and this causes no appreciable obtained by coupling in stages with two difl'erent 1- change in shade. amino-fS-hydroxynapthalene sulfonic acids, and not only For example, the dyestufl of the formula 3) EN (|)H H C(|) (I)CH3 HO I TH: H033 N=N N=N SO3H HOQS S0311 with a monosulfonic acid and a disulfonic acid, but also has an absorption maximum at 610 my when it is cast with two different disulfonic acids. In general, however, in gelatine. The fastness to light of the blue image is the symmetrical diazo-dyestuifs are preferred, inter alia, substantially improved by after-treatment with a copper because they are simpler to make. The latter dyestuffs salt solution of 2 to 5% strength, for example, copcorrespond to the formula per sulfate or copper acetate, and there is only a very slight visual change in shade towards green.

The following examples illustrate the invention, the parts and percentages being by weight.

( r-O O-Xi 3O RiN=N N=NR1 Example I 3 grams of the dyestutf of the formula 8 are dissolved and are more especially dyestulfs of the formulae 35 in 500 ml. of water, and the solution so obtained is added (6) H N (|)H Xi0 0-X1 HO lTIHi Ho s N=N N= -s0 11 O-Xg Xg-O In the Formulae 5, 6 and 7, R X and X have the to 1 liter of a red-sensitized silver bromide gelatine emulmeanings given above, A represents a hydrogen atom or sion which contains approximately to grams of an acyl radical, and one of the two symbols Y bound to silver per kg. of emulsion. The emulsion so obtained is the same naphthalene radical represents a hydrogen atom cast on the desired support, film or paper, and is then and the other represents a sulfonic acid group. dried and exposed.

The dyestuffs of the Formula 1 can be made by the Processing is then carried out as follows: usual known methods. A tetrazo-compound of a diamine (l) Hardening for 5 minutes in an aqueous formaldeof the Formula 2 is coupled with the 1-amino-8-hydroxyhyde solution of 4% strength. naphthalene sulfonic acid or acids in an alkaline medium. (2) Washing with Water for 5 minutes. Coupling may be assisted by the addition of a pyridine Development r 6 minutes in a bath containing, base, such as pyridine itself or picoline. per liter. of water, 50 grams of sodium sulfate, 0.2 gram As stated above the blue dyestutfs of the Formula 1 of l-phcnyl-3-pyrazolidone, 6 grams of hydroquinone, bleach very rapidly in the silver dyestutf bleaching process 35 grams of anhydrous Sodium carbonate, 4 grams of and remain pure blue even at the lowest color density. Potassium bromide and gr of Z iH l The dyestutfs exhibit absorption maxima at 610 to 640 Washing in Water for 5 minutesmu, and they have low subsidiary color densities. Fixation fOf 6 minutes in a Solution of 200 grams It is uncertain to what extent the unexpected bleaching of Sodium thioslllfate and 20 grams of Potassium metawith retention of the original tint is due to the dyestuffs bislllfite in 1000 of Water having little tendency to decompose in stages, that is to Washing in for 5 minutessay, of being reduced not to monoazo-dyestutfs, but prac- COIOI blending for 3 t0 12 minutes With a $0111- tically exclusively to colorless amines, or is due to the tion containing, P liter of Water, 50 t0 80 grams monoazo-dyestuffs having a bluer tint than the known of Potassium bl'omidgi 40 to 30 grams of thiollfea, 35 f0 monazo-dyestufis which contain in the radical of the amine 30 grams of Sulfuric acid Strength if necesnot four, but only two, alkoxy groups. 3, 0-001 g of aminophenazine- The dyestuffs of the Formula 1 are in general sufii- (8) Washing in water for 10 minutes.

ciently fast to diifusion for the silver dyestuff bleaching (9) Bleaching the residual silver for 5 minutes with a solution containing, per liter of Water, 60 grams of copper sulfate, 80 grams of potassium bromide and ml. of hydrochloric acid of strength.

(10) Washing in water for 5 minutes.

(11) Fixation for 5 minutes as described under 5.

(12) Washing in Water for 5 minutes.

After drying, there is obtained a blue image.

The fastness to light of the image so obtained can be substantially improved by treating it for 5 to 10 minutes in a copper sulfate bath for 2 to 5% strength, or in a copper acetate bath of 2 to 4% strength, and then washing it for 5 to 10 minutes in water and drying it.

Similar blue images are obtained with the dyestuffs of the formulae of sodium chloride. After cooling the mixture to 25 C., the dyestutf is isolated by filtration and dried. There are obtained about 100 parts of the dyestutf of the Formula 8. The dyestuffs of the Formulae 9 to 12 can be prepared by the same method. For example, the dyestufl of the Formula 11 is obtained by first running the aforesaid tetrazo-compound into a solution of 32 parts of 1-amino-8- hydroxynaphthalene-2:4-disulfonic acid and 100 parts of sodium bicarbonate in 800 parts of Water, and, after the formation of the diazo-azo-compound, adding a solution of 32 parts of 1-amino-8-hydroxynaphthalene-4:6-disulfonic acid and parts of anhydrous sodium carbonate in 400 parts of water. After 2 hours the dyestuff is precipitated in the manner described above.

HzN OH Ham-c o-ona. HO NH,

l l SO3H O-C2H5 HsCT-O H033 l E038 SO3H HZN on 1130-0 o-oH 110 HN o Ho,s- N=N C N= l o-oH, nae-o H033 -so,rr

no s

11 um 0H H3o )oH, HO 1 m,

l l O-CH; H3C-O H035 1 1103s 80,11 (12) 11:1? OH 1130-? O-CH; H0 b n-1,

1103s N=N N=N 80,3

| O-CzHs Each-'0 1103s sons The dyestuff of the Formula 8 can be prepared as follows:

30.4 parts of 3:6:3:6'-tetramethoxy-4:4-diamino-1:1- diphenyl are stirred in 500 parts of Water with 26 parts of hydrochloric acid of 30% strength, and dissolved, if necessary, by heating to C. After the addition of a further 26 parts of hydrochloric acid, the temperature is lowered to 0 C. by the addition of ice. 14 parts of sodium nitrite, dissolved in 50 parts of water, are added in portions over a period of 10 minutes. There is formed a clear yellow solution of the tetrazo-compound. The solution so obtained is run into a solution of the coupling component, which has been prepared by dissolving parts of 1- amino-S-hydroxynaphthalene-2:4-disulfonic acid and parts of anhydrous sodium carbonate in 800 parts of water, and cooling the solution to 0 to 2 C. by the addition of ice. Coupling takes place rapidly. After 2 to 4 hours, the reaction mixture is heated to 65 C., and the dyestuff is precipitated by the addition of 250 to 400 parts Example 2 200 grams of silver bromide emulsion are sensitized with a red sensitizer, and mixed at 35 C. with a mixture of 0.4 gram of the dyestutf of the Formula 8, 5.0 grams of gelatine, 0.4 gram of a condensation product of dicyandiarnidine with formaldehyde, and cc. of Water. The emulsion so obtained is cast on a suitable supportj Example 3 The procedure is the same as in Example 2, with the exception that 0.28 gram of barium chloride is added, instead of the condensation product of dicyandiamidine. Stabilizers, spreading agents, such as saponin, and/or hardening agents may be incorporated with the casting solutions described in Examples 2 and 3 before they are cast.

Example 4 3 grams of the dyestutf of the formula 7 8 are dissolved in 500 ml. of water, and the solution is bleaching process which contains silver halide and a disazoadded to 1' liter of a red-sensitized silver bromide gelatine dyestufI of the formula which contains, per liter, 30 to 35 grams of silver. 1 gram X, (I)-X1 of 1:1'-diphenyl-4:4'-biguanide in the form of its acetate or hydrochloride dissolved in 100 ml. of water is added 5 RlN=N-- ON=NR2 dropwise while stirring. This renders the dyestufl' com- I pletely fast to diffusion. The dyestulf-gelatine emulsion so 0Xz Xvi) obtained is cast on a suitable support, if desired, as one of in which R and R each represents the radical of a 1- the layers of a three-color multi-layer material, and procamino-8-hydroxynaphthalene disulfonic acid which is essing is carried out as described in Example 1. The devel- 10 bound to the azo linkage in 7-position, and X and X each oped and after coppered l layer possesses a hi h degree represents a member selected from the group consisting of of fasmess to light an alkyl group and an alkoxyalkyl group.

The dyestuff of the Formula 13 can be made as follows: A P p c layer i l for the silver dyestuff 53.6 parts of 3 6:3z6 tetra-e-ethoxy-ethoxy-4:4-dibleaching process which contains silver halide and a disazoamino-1:1'-diphenyl are stirred for several hours in 600 15 dyestufi of the formula parts of Water in the presence of 26 parts of hydrochloric H3C O ONO acid of 30% strength. After the addition of ice and a further 26 parts of hydrochloric acid of 30% strength, 14 1 l 1 parts of sodium nitrite in the form of an aqueous solution O CH3 of 20% strength are added dropwise in the course of in which R1 and R2 each represents the radical of a minutes at a f p 'f 'f of 0 to The tetrazocom' amino-8-hydroxynaphthalene disulfonic acid which is pound so obtained 15 st1rred for 1 hour, and then added bound to the am li k i 7-p0sifi0n, to a solution of parts of 1- mi 1 Y Y- P 3. A photographic layer suitable for the silver dyestuff lene-2z4-dlsulfonrc acid, parts of anhydrous sodium car- 25 bleaching process which contains silver halide and a disbonate and 40 parts of commercial picoline in 800 parts of azo-dyestutf of the formula H N H H Ct-O -CH HO NH H0 3 I N N N S O H HO S .O

3 CH H c 3 Water. The temperature is kept at 0 to 2 C. by the addi- 4. A photographic layer suitable for the silver dyestufi tion of ice. Coupling takes place rapidly, and the dyestulf bleaching process which contains silver halide and the can be obtained in an easily filterable form by the addition disazo-dyestufi of the formula of 250 parts of sodium chloride. The dyestulf is then iso- 5. A photographic layer suitable for the silver dyestuff lated by filtration, the adherent picoline is removed by bleaching process which contains silver halide and the washing with aqueous alcohol, and the dyestulT is dried. disazo-dyestulT of the formula HzN (|)H H5C:O OC2H5 H0 NH,

S0 11 0-C4H5 HaC'r-) H0 8 110 's do h 6. A photographic layer suitable for the silver dyestuff What 1s claimed is: bleaching process which contains silver halide and the 1. A photographic layer suitable for the silver dyestuff disazo-dyestufi. of the formula ms: or! Ego-0 o-crr; HO In i0 7. A photographic layer suitable for the silver dyestufi bleaching process which contains silver halide and the disazo-dyestuif of the formula H N (I)H H3C(') (IF-CH3 HO NH; s N=N-C QN=N (J-CH3 H3CO H035 8. A photographic layer suitable for the silver dyestufi bleaching process which contains silver halide and the disazo-dyestuff of the formula H N OH H;C(l) (I)CH3 EI[O 11TH: H0; -N=NQ N=N SO H OC2 s HsCr-O 9. A photographic layer suitable for the silver dyestufi bleaching process which contains silver halide and the disazo-dyestufi of the formula H5C2OCH:CH:O O-CH2CH2-OC2H5 i 6 l I a 11038 -N=N%t N=r -SOaH a f CH2 CH2 l H038 I I 80311 (IE2 (IE2 O-CzH5 H5C2-O References Cited by the Examiner UNITED STATES PATENTS 2,304,884 12/1942 Carroll 9699 2,612,448 9/1952 Gaspar et al. 9699 FOREIGN PATENTS 56,699 10/1952 France.

NORMAN G. TORCHIN, Primary Examiner. J. T. BROWN, Assistant Examiner, 

1. A PHOTOGRAPHIC LAYER SUITABLE FOR THE SILVER DYESTUFF BLEACHING PROCESS WHICH CONTAINS SILVER HALIDE AND A DISAZODYESTUFF OF THE FORMULA 